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New Research Finds Direct Correlation Between Pollution and Infant Mortality

December 10, 2012

By Jenny Li Fowler, Harvard Kennedy School Communications

There is a growing concern about how pollution may impact health outcomes in developing countries. In a new Harvard Kennedy School (HKS) Faculty Working Paper titled “Does the Effect of Pollution on Infant Mortality Differ between Developing and Developed Countries? Evidence from Mexico City,” three researchers seek to determine how lessons learned from one of the world's most populated cities might affect the thinking about clean air standards around the world.
Authors Rema Hanna, HKS associate professor of public policy, Eva Arceo (CIDE), and Paulina Oliva of University of California-Santa Barbara estimated the effect of pollution on infant health in Mexico City. To compute their estimates they tried to disentangle pollution and income: Wealthy people may live in low pollution areas, whereas poor people might be more likely to live in high pollution areas. Thus, it may look like pollution has an effect on health, but it is all driven by income.
So, the researchers took economic levels out of the equation by using the meteorological phenomenon known as thermal inversion. “We want variation in pollution that has nothing to do with economic levels. Thermal inversion is helpful because it’s not correlated with income status,” said Hanna.
Once the mitigating factors were extracted from their analysis, the authors found that dirty air does indeed result in more infant deaths. “We find statistically significant effects of pollution on infant mortality in Mexico City,” the authors concluded.
They then compared their estimates with those from other existing studies. They hypothesized that their estimates may be different due to a variety of factors. For example, mortality rates are significantly higher in many developing countries and it is possible that pollution may simply have a greater effect on infants already weakened by other factors. Or the opposite effect is possible in that a marginal increase in pollution may be negligible if the factors supersede the pollution effect. The effect of pollution on health may also be highly dependent on behavior. “Avoidance behavior may be costlier in the developing world given less access to health care and lower quality housing stock,” write the authors.
Their hypothesis was true: they find that some pollutants, like carbon monoxide, exert a bigger effect on infant mortality in Mexico City than in the United States.
“When people are making decisions about enacting stricter air pollution regulations in developing countries I hope they look both the cost of the program but also the benefits, so our paper sheds light on some of the benefits,” said Hanna.Hanna’s work focuses on understanding how to improve the provision of public services in developing countries, particularly for the very poor. Her work in this area has ranged from testing models of corruption and bureaucratic absenteeism in the field, to understanding how discrimination affects disadvantaged minority groups. Currently, she has been working on a series of field projects to understand what types of individuals are selected to receive social programs under different forms of targeting mechanisms.

“When people are making decisions about enacting stricter air pollution regulations in developing countries I hope they look both the cost of the program but also the benefits, so our paper sheds light on some of the benefits,” said Hanna.